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Emag Batteries

Hey all, I havent played in about 5 years being I went into the Air Force and now im back and looking to blow the dust off my emags, I go and hook up my battery charger to the packs (I have two emags) and the LED on the charger just stays green the whole time, even though I tried them and they were so dead they couldnt even trip the sear with it gassed up but I know they are holding a slight charge I left one on there for a few hours and then hooked it up and it was working but who knows for how long.. Is there a way to tell if the batteries are still in decent condition by measuring like an output voltage or current or something? Thanks

Its tough to measure the condition of a battery pack without the proper equipment that can measure and calculate the charge values. A fully charged battery pack should read somewhere around 18V. You have to measure it after it sits for a few hours following a charge cycle, so that you are getting the true voltage and not the residual voltage that is only there due to the chemical activity of the charge and will dissipate.

If you have a multimeter, you can measure the voltage of the fully charged battery. Then attach the solenoid to the battery pack with the multimeter already attached. Once the voltage settles to a readable value after a second, read it and disconnect. It should only be on for a second to prevent heating of the solenoid. If the voltage dips significantly, you have a bad pack. If it stays relatively constant, the pack is good. The voltage shouldn't dip below 16.8v. The starting no load will be higher than that, usually greater than 18v. Make sure you measure the starting value after the pack has been off the charger for a few hours or it will not be a true representation of the steady full battery level.

If your batteries have been sitting dead for a significant amount of time, there is a real possibility that they are bad. Dead cells develop deposits on the electrodes which impede the ability of the cell to deliver a current to the load or receive current from a charger. Once these deposits are present, they are hard, if not impossible, to remove.

Except for the Automag in front, its usually the man behind the equipment that counts.

I just rebuilt my Emag battery pack. All you need is 14AAA NiMH Batteries A NICE HOT IRON
and quick hands. You dont want to over heat any of the cells. I bought Rayovacs they are rated at 1000mAh nearly twice the capacity of the factory pack. WOOT! You could go Li poly. That would lighten things up a bit. A 14.8 V pack should more than do the job but you would have to buy a balance charger. The new intelligent chargers display the capcity of your batteries and can charge nicd, Pb acid, NIMH, and all the Lithium family of batteries including balance charging.

How to Fly: Throw yourself at the ground and miss. "Hichikers guide to the Galaxy"

I just rebuilt my Emag battery pack. All you need is 14AAA NiMH Batteries A NICE HOT IRON
and quick hands. You dont want to over heat any of the cells. I bought Rayovacs they are rated at 1000mAh nearly twice the capacity of the factory pack. WOOT! You could go Li poly. That would lighten things up a bit. A 14.8 V pack should more than do the job but you would have to buy a balance charger. The new intelligent chargers display the capcity of your batteries and can charge nicd, Pb acid, NIMH, and all the Lithium family of batteries including balance charging.

Can you tell me more about rebuilding the battery? I think mine is pretty dead and KC the 1000mah battery guy is awol.

I can buy one from AGD, but it seems easy to get more MAHs if you assemble it yourself with off-the-shelf cells.

Put the 14 AAA cells in series but make sure the physical shape of the layout is the same as the original. If you can find the tabbed batteries, it is easier to solder them together than with flat or button top cells. Flats are good because they allow wires or tabs to be added between cells. The button top cells are physically longer so you don't have as much room left to add tabs or wire to join the cells. The button top cells will work in the pack, but you must be much more careful when you join them in order to keep the pack length short enough to fit in the holder.

Lipos are smaller batteries, so you should be able to find a configuration that will fit easily. If you do get Lipos, you need to buy a special battery charger that will charge them. Lipos are more expensive as well, so be prepared for the extra cost.

14.8V would cause a reduction in power by about 22%. That should still trip the sear, but it would cut into any buffer needed to maintain operational consistency in all instances. That means you better keep the mechanism clean. It would probably be better to add an extra cell. See below for an explanation.

In reality, Lipo cells have a fully charged voltage value of 4.25V so most charger limit it to 4.2V. The minimum safe voltage is 3V so most use a cutoff of 3.3V. That gives a four cell pack a voltage range of 13.2V to 16.8V. The discharge line from 16.8V to 13.2V is fairly linear and results in the 14.8V nominal rating. The calculations show a 15V average but in reality its not perfectly linear so the real average is 14.8V.

NiMh cells have a fully charged voltage value of about 1.4V but it drops to 1.3V very quickly so the 1.3V value is used for the upper value when determining average operating outputs. The minimum voltage is 1.0V, but the drop from 1.1V to 1.0V occurs very quickly so the 1.1V value is used for the lower voltage. The resulting average is 1.2V which is the industry value used for packaging. A 14 cell pack rated at 16.8v actually ranges from 18.2V to 15.4V.

checking the voltage values of the lowest value for each pack type, it shows a reduction in power by 27% from NiMh which is worst than the 22% calculated using nominal values. As the pack gets discharged, you might end up with firing issues using a 14.8V LiPo pack.

i've seen an 18.5V 4 cell and a 22.4V 5 cell, can i go with the 5 cell and not fry my board?

18.5V packs are 5 cell and 22.4V packs are 6 cell. The 6 cell 22.4V pack won't fry the board but it will cause the solenoid to draw more current than it does now. It already draws a lot. Drawing more current will result in additional heating of the wire in the coil which will require an investigation into the solenoid specs so that the max amount of on-time and number of pulses per second are not exceeded. I don't know that value off hand.

The 18.5V pack will operate very similar to the stock pack so the additional current draw shouldn't be an issue. I would go with this one over the 22.4V pack, plus the 18.5V pack will be lighter than the 22.5V pack.

There are no specific packs available. You'll have to get one made. Find a dealer that makes battery packs and find out what the dimensions are for a pack that meet the specs you need. For LiPo, they are 18.5V at 3A of current with a capacity of about 600mAh. If you can't match the dimensions of the emag battery holder, then you will have to make a new holder to fit the new pack dimensions.

There are no specific packs available. You'll have to get one made. Find a dealer that makes battery packs and find out what the dimensions are for a pack that meet the specs you need. For LiPo, they are 18.5V at 3A of current with a capacity of about 600mAh. If you can't match the dimensions of the emag battery holder, then you will have to make a new holder to fit the new pack dimensions.